Circuit controlling apparatus



P. N BOSSART CIRCUIT CONTROLLING APPARATUS Sept. 27, 1932.

Filed Jan. 22

INVENTOR P, Bossar 44 ATTORNEY Patented Sept. 27, 1932 UNITED STATESPATENT OFFICE 8c SIGNAL COMPANY, SYLVANIA OF SWISSVALE, IENNSYLVANIA, ACORPORATION OF I'ENN- CIRCUIT CONTROLLING AIPFA'BATUS Application filedJanuary 22, 1929. Serial No. 834,345.

My invention relates to circuit controlling apparatus, and has for anobject the provision of novel and improved means for op erating contactsat relatively low frequencies, such for example, as frequencies of theorder of 1 to 3 cycles per second.

I will describe several forms of apparatus embodying my invention, andwill then point out the novel features thereof in claims.

In the accompanying drawing, Fig. 1 is a view, partly in verticalsection and partly diagrammatic, showing one form of circuit controllingapparatus embodying my invention. Fig. 2 is a diagrammatic view showinga modification .of a portion of the apparatus shown in Fig. 1. Fig. 3 isa fragmentary view showing a modification of another portion of theapparatus shown in Fig. 1.

Similar reference characters refer to similar parts in each of theviews.

I .Referring first to Fig. 1, the reference character 1 designates aframe supporting three tubular members 2 2 and 2, with their axesvertically disposed. The outside of each of these tubular members isscrewthreaded, and each member coacts with a threaded hole in the frame1, so that the vertical position of each tubular member may be veryaccurately adjusted by turning the member in the frame.

The reference characters 3*, 3 and 3 designate coiled springs, the upperend of each of which springs is attached to the associated tubularmember2, 2 or 2, so that these springs hang in such positions that theiraxes are vertically disposed. Attached to the lower end of spring 3 is aplunger 4*, a weight 6, and a movable contact member 7 The springs 3 and3 are provided with corresponding plungers, weights, and contactmembers. Each contact member 7 coacts with a fixed contact member 8 inthe manner hereinafter explained. Each weight 6 is preferablyadjustable, and for this purpose it may be'in the'form of a cup adaptedto receive lead shot. Each plunger 4 coacts with an associated solenoid5 in such manner that if the solenoid becomes energized when theassociated spring is at rest in its position of equilibrium, the lowerend of the spring will e lifted above its position of equilibrium.

The amount of the stretch of each spring at its equilibrium pointdetermines the frequency of the vibration of the spring along itsvertical axis. vibration is equal to where L is the stretch of thespring and G is the acceleration due to gravity. It is, therefore, veryeasy todetermine just how much any spring should be stretched for agiven frequency. Thus for two cycles per second, the stretch should be 2inches.

Each solenoid 5 is preferably iron clad except through the center. Oneterminal of each solenoid is connected with the associated fixed contactmember 8 through a resistance 11, and the other terminal is connectedwith one of the three points 10 of a contact device comprising a movablemember 9 which is adapted to engage-any one of the points 10. Themovable member, 9 is connected with one terminal of a relay R, and theother terminal of this relay is connected with one terminal of a batteryB. The remaining terminal of battery B is connected with the frame 1. Itwill be seen, therefore, that any one of the solenoids 5 and theassociated contact circuit with relay R and battery B, depend--v ingupon the position of the contact member 9. Each contact 7-8 is soadjusted that it is closed when the associated spring is in its positionof equilibrium, but isopened immediately after the lower end of thespring is raised above such position.

The operation of the apparatus shown in Fig. 1 is as follows: Assumingthat the contact 9 is in the position shown in the drawing, and that thespring 3* is at rest in its position of equilibrium, solenoid 5 will beenergized, thus drawing the plunger 4: upwardly and so opening contact78'*. This will break the circuit for the solenoid 5, and so the lunger4 and weight 6 will pull the assem ly down, thereby stretching 7-8 maybe included in The complete period of a spring 3. Contact 78 will againclose at or near the equilibrium point, so that solenoid 5" will againbecome energized to raise the plunger and weight. It follows 5 thatoscillations will soon be set u and maintained, and that the frequency0? such oscillations will be determined almost entirely by themechanical properties of the spring and its attached mass. It should benoted that current flows for almost exactly one-half the time, that is,for the time that contact 7 8 is closed. It follows that relay R isperiodically energized and de-energized, the periods of energization anddeenergization being almost equal, and the rate of operation of itscontact being determined by the frequency of oscillation of the spring3.

If contact member 9 engages with contact point 10", the rate ofoperation of relay R will depend upon the characteristics of the spring3", and its attached mass and if contact member 9 is in engagement withcontact point 10, the rate of operation of relay R will depend upon thecharacteristics of spring 3 and its attached mass.

As an example, the characteristics of the apparatus may be such that therate of oscillation of spring 3' is 3 cycles per second, the

80 rate of oscillation of spring 3 is 2 cycles per second, and the rateof oscillation of spring 3 is 1 4; cycles per second.

Relay R may be used for any suitable purpose. As here shown, it isemployed to periodically interrupt the supply of automatic traingoverning current to the rails of a railway track. These rails aredesignated 13 and 13?, and they are divided by insulated joints 14 toprovide a track section.

Alternating train governing current is supplied to the rails by agenerator G, and the circuit includes contact 12 of relay B, so thateach time that relay R is energized, alternating current is supplied tothe rails,

whereas each time relay R is de-energized, the supply is interrupted.The train carried apparatus which responds to the train governingcurrent thus periodically supplied to the rails forms no part of mypresent invention and is omitted from the disclosure.

Considering now any one of the spring, plunger, and weight assemblies,it will be noted that when oscillations are started, the solenoid 5 isenergized while the weight moves from its middle position to its lowestpoint, as well as when it is rising from its lowest point to its middleposition. Thus it would be expected that the assembly would be sloweddown while descending as much 50 as it is accelerated while rising, andthat no amplitude reater than the first kick would be obtained and nofree vibration set up. This is, in fact, the case when the solenoidcurrent at once attains its steady value. This 05 could be guardedagainst by a system of relays which would energize the solenoid when andonly when the plunger is rising, but I have discovered that thiscomplication is unnecessary if the time constant of the energizingcircuit is of the same order as the natural period of oscillation of theassembly. This condition is easily realizable in practice forfrequencies of the order of one to three cycles per second. Thus if thetime constant of the solenoid circuit is equal to the half period ofoscillation of the assembly, the average current value for the quarterperiod during which the assembly is rising is 2.61 times that for thequarter period in which the assembly is moving downwardly, so that theacceleration while the assembly is rising is much reater than theretardation while descen ing, with the result that relatively largeamplitudes only slightly forced are built up.

It is, however, desirable to limit the amplitude to a convenient amountand at the same time to have a strong starting force with relatively lowvoltages. I find that this can be accomplished b making the length ofthe 9 solenoid about tlie same as the desired amplitude of the motion ofthe plunger, andadj usting the spring support so that in its equilibriumposition with no current in the solenoid,'the upper end of the plungeris at a position 40% of the length of the solenoid above the lower edgeof the solenoid The force from this point to the lower end of thesolenoid varies from a maximum to zero, so that if the amplitude becomeslarge, there is no force acting on the plunger for the part of itsoscillation during which it is below the .lower level of the solenoid,and a smaller force is exerted near the bottom of the solenoid than thatexerted at the equilibrium point. This characteristic is useful becauseit permits a considerable starting force at low voltage and because itlimits the amplitude of vibration without artificially increasing thedamping. Artificial increase of 1 damping would affect the frequency ofoscillation.

The purpose of resistances 11 is to adjust the time constants of thecircuits for the solenoids to the order of one-half of the naturalperiod of oscillation of each assembly. In practice this resistance canbe wound into the coils 5, 5" and 5 if desired.

Referringnow to Fig. 2, the apparatus is the same as that shown in Fig.except that the solenoid circuits include the primary of a transformer Tinstead of the winding of a relay R. The secondary of this ){transformeris connected with the winding 1 of a polarized relay R the ctntact 12 oiwhich com trols the supply of alternating current to the track rails 13and 13. Each time the primary circuit is closed an impulse of onepolarity is supplied to relay R and each time the primary circuit isopen an impulse of 0 the opposite polarity is supplied to this relay.The polarized armature 16 is biased to remain in either-position towhich it is moved, and so it follows that the operation of contact 12 isthe same as the operation of contact 12 in Fig. 1. The apparatus shownin Fig. 2 will probably require a smaller amount of power than theapparatus shown in Fig. 1.

As stated hereinbefore, the assembly including the spring 3 may beadjusted to oscillate at a frequency of 1% cycles per second. Thisrequires a spring stretch of about 5 inches. In order to reduce theheight of the apparatus, this stretch may be obtained by a cantileverspring instead of a coiled spring. Referring to Fig. 3, the referencecharacter 18 represents a cantilever spring, the lower end of which isfixed and the upper end of which is connected with the plunger 4. Inother respects the apparatus shown in Fig. 3 is the same as that portionof Fi 1 which is associated with the spring 3. T e modification shown inFi 3 provides greater compactness than the form shown in Fig. 1.

One feature of apparatus embodying my invention is that it requires verylittle power for operation, because the losses in the timing mechanismare ver small. Another feature is that the period 0 oscillation of eachassembly is constant to a marked degree, and is independent oftemperature and applied voltage, since it is determined by the elasticconstants of the spring material and the amount of mass attached to thespring. The variation of the modulus of rigidity upon which springstiffness depends with temperature, is such as to affect the frequencyonly about 1% or less for a change in temperature of 180 F.

Although I have herein shown and de scribed only a few forms ofapparatus embodying my invention, it is understood that various changesand modifications may be made therein within the scope of the appendedclaims without departing from the spirit and scope of m invention.

Having thus descri ed my invention, what I claim is:

1. Circuit controlling apparatus capable of sustaining self oscillationand accurately a-djustable as to frequency, said apparatus comprising aspring one end of which is fixed in a position adjustable as to heightand the other end of which is free to move in a substantially verticalline, a plunger attached to the free end of said spring, a weightadjustable in mass attached to the free end of said spring, a flexiblecontact member having one end fixed, a movable contact member attachedto the free end of said spring and engaging the free end of saidflexible contact member whenthe free end of said spring is in itsposition of equilibrium but not when the sprlng is raised" from suchposition, and a fixed solenoid controlled by the contact formed by saidtwo contact members and coacting with said plunger to raise the free endof said spring from its position of equilibrium, the parts being soproportioned and so adjusted that if said solenoid is energized over thecontact formed by said two contact members said spring and weightassembly will oscillate at substantially its natural period.

2. Circuit controlling apparatus capable of sustaining self oscillation,said apparatus comprising a spring one end of which is fixed and theother end of which is free to move in a substantially vertical line, aplunger attached to the free end of said spring, a flexible contactmember having one end fixed, a movable contact member attached to thefree end of said springand engaging the free end of said flexiblecontact member when the free end of said spring is in its position ofequilibrium but not when the spring is raised from such position, and afixed solenoid controlled by the contact formed by said two contactmembers and coacting with said plunger to raise the free end of saidspring from its position of equilibrium, the parts being so proportionedthat the time constant of said solenoid is of the same order as thenatural period of said spring and plunger.

3. Circuit controlling apparatus capable of sustaining self oscillationand accurately adjustable as to frequency, said apparatus comprising aspring one end of which is fixed in a position adjustable as to heightand the other end of which is free to move in substantially a verticalline, a plunger attached to the free end of said spring, a weightadjustable in mass attached to the free end of said spring, a flexiblecontact member having one end fixed, a movable contact member attachedto the free end of said spring and engaging the free end of saidflexible contact member when the free end of said spring is in itsposition of equilibrium but not when I the spring is raised from suchposition, and a fixed solenoid controlled by the contact formed by saidtwo contact members and coacting with said plunger to raise the free endof said spring from its position of equilibrium, the length of saidsolenoid being a proximately the same as the desired amp itude of motionof said plunger and the parts being so adjusted and so arran ed thatwhen the free end of said spring is 1n its position of equilibrium theupper end of said plunger will be at a position approximately 40% of thelength of the solenoid above the lower edge of the solenoid, whereby theamplitude of motion of the plunger is limited without artificiallyincreasing the damping of the moving parts.

In testimony whereof I afiix my signature.

PAUL N. BOSSART.

